The invention pertains to visual, alarm indicating output devices for monitoring systems. More particularly, the invention pertains to adjustable forms of such output devices.
Known types of alarm systems often include audible and/or visible output devices. Two nominal voltage ranges, 8 to 17 and 16 to 33, are available for driving such devices.
Known visible output devices can output a predetermined light level, expressed in candelas, Known devices have provided some flexibility in being able to select an output light level for a predetermined driving voltage range. In known devices, this has been accomplished in several different ways.
In one type of known product, components are physically changed in the field to produce an installed product of desired brightness. This could be done with discrete components or plug-in modules.
Alternately, components can be switched, in a hardwired design using a multi-position switch. In this configuration, all components are installed and selecting one setting of the switch couples the respective selected components to the rest of the circuit to produce a hardwired circuit configuration which results in the desired brightness. Unselected components are switched out of the circuit and are nonfunctional. In this product, the switch is located on the electrical mounting box side of the strobe unit.
In yet another configuration, a front mounted slide switch can be set to a desired position and then concealed with a snap-on cover. In this configuration, a charging frequency parameter is altered by the slide switch to produce a desired brightness. This product does not alter a duty cycle parameter in a fixed charging frequency environment. Instead, a multi-terminal inductor is combined with different resistors to alter a charging frequency of the strobe.
It has been recognized that there is an advantage in reduced manufacturing costs and enhanced flexibility in being able to provide a single adjustable visual output device which can be connected to alarm systems which output either of the available driving voltage ranges. One such visual output device has been disclosed in U.S. patent application, Ser. No. 09/767,897, entitled xe2x80x9cProcessor Controlled Strobexe2x80x9d, filed Jan. 23, 2001, assigned to the assignee hereof and incorporated herein by reference. The strobe unit therein discloses circuitry for selecting a candela output substantially independently of the applied driving voltage.
There continues to be a need for reliable and easy to use adjustment structures that can be used with variable output strobe units. Preferably such structures can be used to set the desired light output level at installation without having to be concerned about the amplitude of the applied driving voltage. It would also be desirable if the setting was visible after the fact but at the same time was substantially tamper-proof.
An adjustable alarm indicating device has an indicating side and a mounting side. An output parameter of the alarm indicator can be set on the mounting side. When installed, the set parameter value can not be altered.
In one embodiment, a multi-candela output device has a housing which carries a source of illumination. The source is visible after the device has been installed.
Prior to installation, an output candela level can be set by manually adjusting a slidable or rotary member mounted on a surface of the device which is not visible or accessible once the device has been installed. An output indicator, coupled to the adjusting member is visible after installation.
In another aspect, a visual alarm unit has a mounting structure for attachment to an electrical box. When attached to the box, a first side of the unit extends toward the interior of the box providing a secure tamper-proof region that is not accessible. A second side of the unit carries the visual output device and extends away from the box.
An output light level can be manually set at the first side by means of a setting switch or adjustable mechanical member. When installed on the box, the setting switch or member is contained in the tamper-proof region.
A visual output indicator is located on the second side. The output indicator is linked to the setting switch or adjustable member and provides visual confirmation of the preset output light level.
Thus, prior to installation, the output light level of a respective unit can be easily set without any need for special tools., Once installed, the setting of the unit can not be altered but it can be visually confirmed.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.